Mesostructured g-C₃N₄ nanosheets interconnected with V₂O₅ nanobelts as electrode for coin-cell-type-asymmetric supercapacitor device

In this study, low-cost, noble-metal-free, ecologically friendly, high-performance coin-cell-type supercapacitors are constructed using an efficient one-pot approach. Two novel nanostructures comprising V₂O₅ nanobelts—one with and one without cetyltrimethylammonium bromide (CTAB)-modified g-C₃N₄—are synthesized via a hydrothermal process (g-C₃N₄ nanosheet (CN)/VO and CTAB-modified pore-rich g-C₃N₄ nanosheet [CCN]/VO nanostructures, respectively). CTAB is used as a sacrificial template to generate mesoporous structures in the g-C₃N₄ nanosheets. The CCN/VO nanostructure exhibits a larger surface area (73.5 m²/g) than that of CN/VO (54.1 m²/g) and superior specific capacity (192.3 mAh/g/0.5 A/g). In addition, an asymmetric capacitive device composed of the CCN/VO nanostructure and activated carbon is fabricated. It exhibits a remarkable energy density of 96.6 Wh/kg at 811.0 W/kg in the voltage frame of 1.5 V, along with a remarkable cycling stability of 90.2% over 5000 cycles. Moreover, the CCN/VO nanostructure electrode is used to reproduce experimental cyclic voltammetry curves in a numerical simulation model. The unique CCN/VO with a 2D/1D nanostructure exhibits superior electrochemical capacitor characteristics. This result could inspire novel nanostructured electrode materials that can potentially be used in high-performance supercapacitor applications.